Lapping machine



June 2, 1970 5, BOETTCHER 3,515,115

LAPPING MACHINE Filed Sept. 14 1967 2 Sheets-Sheet 1 -fnflnlarw Sign/Len @Baeiicfim: fyfl'mm, mi

2 Sheets-Sheet 2 June 2, 1970 s. A. BOETTCHER LAPPING MACHINE Filed Sept. 14, 1967 United States Patent Int. Cl. B2411 53/02 US. Cl. 125-11 '10 Claims ABSTRACT OF THE DISCLOSURE Support and drive means for a contour control member positionable with the lower surface thereof in engagement with a lapping disc for dressing the lapping surface of the disc.

BACKGROUND OF THE INVENTION Field of the invention The present invention relates generally to lapping machines and more particularly to apparatus for controlling the contour of lapping surfaces.

Description of the prior art In general, a lapping machine comprises a lapping disc rotatably driven about a vertical axis, and one or more retaining and truing rings which rest on the lapping disc and which are normally rotatable about their own axes freely by frictional contact with the disc. These rings are provided for holding work pieces within them against movement with the rotating lapping disc, and for wearing the lapping surface to tend to keep it planar. However, in this arrangement, more wear of the lapping surface occurs in the inner annular portion than in the outer annular portion. Therefore, to maintain practical flatness of the lapping surface within acceptable limits, another controlling element must be introduced.

One approach to this problem, as disclosed in the copending application of Stephen A. Boettcher, Ser. No. 416,825, filed Dec. 8, 1964, now Pat. No. 3,374,582, has been to selectively engage one or more independent wear members exclusively with the outer annular zone of the lapping surface. Each wear member rotates about its own axis by frictional contact with the rotating lapping disc, and during such rotation effects the desired contour corrective action. In this system, a pneumatic assembly is provided for raising and lowering the wear member and for selectively urging the latter under pressure into engagement with the lapping disc.

SUMMARY OF THE INVENTION In accordance with the present invention, a contour control member is coupled to the lower end of a vertical floating spindle. As one feature of the invention, the free weight of the spindle is utilized to provide the desired pressure under which the contour control member is urged into frictional engagement with the lappind disc. As another feature, mechanical adjustment means is provided for selectively engaging and raising the spindle whereby to withdraw the contour control member from engagement with the lapping disc. As a further feature, the spindle is adapted to be power rotated for increasing the rotational velocity of the contour control member whereby required contour corrective action may be effected more rapidly, with a single wear member, than heretofore. As a still further feature, the contour control member is coupled to the spindle by novel flexible driving means which provides a swivel connection having a low swivel point for optimum operation of the contour control member.

DESCRIPTION OF THE DRAWINGS FIG. 1 is a side elevational view, with portions being broken away and shown in section, of a lapping machine incorporating the contour control apparatus of the present invention;

FIG. 2 is an enlarged vertical median sectional View of the contour control apparatus of FIG. 1, with the contour control member disengaged from the lapping disc;

FIG. 3 is a sectional view corresponding generally to FIG. 2, but showing the contour control member in engagement with the lapping disc; and

FIG. 4 is a fragmentary sectional view, taken substantially along the line 44 in FIG. 1, looking in the direction indicated by the arrows.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FIG. 1, there is indicated generally by the reference numeral 10 a lapping machine with which the apparatus of the present invention may be incorporated. The lapping machine 10 comprises framework including a lower housing section 12, an upright rear-end housing section 14, and an upper overhanging housing section 16 having a lower horizontal wall 18.

The lower housing section 12 provides support for a horizontal annular lapping disc 20 and a staging table 22 surrounding the lapping disc. Selective rotation of the lapping disc 20 about a vertical axis is effected by drive means comprised, for example, of an electric motor 24 and a speed reducer unit 26.

Mounted in the upper housing section 16 are four pneumatic piston and cylinder assemblies 28, two one one side of the machine and two on the other side. Each of the pneumatic assemblies 28 includes a cylinder 30 and a piston rod 32. The lower ends of the piston rods 32 are secured to horizontal pressure plates 34 which fit, with slight clearance, within truing and retaining rings 36 resting on the lapping disc 20.

The rings 36 slightly overlap the inner and outer peripheries of the annular lapping surface of the disc 20. When the lapping disc 20 is rotated, the truing rings 36 rotate relative to the pressure plates 34 about the axes defined by the piston rods 32 whereby to serve to dress the lapping surface of the lapping disc 20 for substantial maintenance of its planar condition. Work pieces (not shown) to be lapped are adapted to be confined within the truing rings 36 below the pressure plates 34 therein. During the lapping operation, a freely flowing mixture of abrasive particles and an oil carrier is fed to the lapping disc 20 through discharge spouts 38 in a known manner.

To supplement the normal dressing action of the truing rings 36, the present invention contemplates the provision of power-operated independent contour control apparatus indicated generally by the reference numeral 40.

The apparatus 40, as shown in FIGS. 2 and 3, comprises a vertical tubular casing 42 extending through and secured to the housing wall 18. Threaded in the lower end of the casing 42 is an axially adjustable sleeve member 44. Extending through the casing 42 and sleeve member 44 is a floating spindle 46 provided with a radial shoulder 48. A ball bearing assembly 50 is secured on the upper section of the spindle 46 and is axially movable within the casing 42, while a ball bearing assembly 52 is secured in the sleeve member 44 and is axially movable along the lower section of the spindle 46.

A circular disc-like contour control member 54 is connected by coupling means 56 to the lower end of the spindle 46. The lower face of the member 54 is formed with a central circular recess 58 and a concentric annular recess 60 in which is secured, as by epoxy cement or the like, an annular wear ring 62. The wear ring 62 must be fabricated of a material having a greater abrasion resistance than the material of the lapping disc 20 and is preferably of a high wear resistant material such as boron carbide. The upper portion of the member 54 is also provided with a central conical bearing seat 64 which is recessed below the plane of the upper surface of the member 54.

The coupling means 56 is comprised of a spherical bearing element 66 engaged in the seat 64-, with the top surface thereof lying in the plane of the upper surface of the member 54. A flexible metal diaphragm 68 is secured to the member 54 across the upper surface thereof and engages the bearing element 66. Additionally, interconnecting means in the form of a collar member 70 is secured both to the lower end of the spindle 46 and to the central portion of the diaphragm 68. The contour control member 54 is thus rotatable, and vertically movable, with the spindle 46.

As shown in FIG. 4, the contour control member 54 is positioned circumferentially intermediate of the two adjacent truing and retaining rings 36 at the outer annular Zone of the lapping disc 20 in slightly overlapping relation with respect to the outer periphery thereof. The diameter of the contour control member 54 is substantially less than the diameter of each of the rings 36. Also, the radial distance between the axis of rotation of the lapping disc 20 and the axis of rotation of the contour control member 54 is greater than the radial distance between the axis of rotation of the lapping disc and the axis of rotation of each of the truing rings 36.

The spindle 46 and contour control member 54 are adapted to be power rotated by an electric motor 72 (FIG. 1). The motor 72 is secured to a bracket 74 carried by an inverted generally U-shaped frame 76 extending lengthwise centrally of, and supported by, the housing wall 18. The frame 76 is suitably apertured to permit the casing 42 and spindle 46 to project therethrough. The motor 72 has a vertical drive shaft 78 on which is secured a crown pulley 80. An endless belt 82 extends about the pulley 80 and the upper section of the spindle 46 for establishing a driving connection therebetween.

When corrective treatment of the lapping surface of the lapping disc 20 is necessary, the adjustable sleeve member 44 is threaded axially downwardly from the position shown in FIG. 2 to the position shown in FIG. 3. This permits the lower horizontal surface of the contour control member 54 to engage the lapping surface of the lapping disc 20. At the same time, the bearing assembly 52 is withdrawn from engagement with the radial shoulder 48 of the spindle 46 and the full weight of the latter bears downwardly on the contour control member 54. A contact pressure of up to pounds per square inch between the control member 54 and the lapping disc has been found desirable. In this connection, the spindle 46 is designed with a mass such that the free weight of the spindle bearing on the control member 54 serves to provide the desired pressure under which the control member is urged into frictional engagement with the lapping disc.

Also, during corrective treatment, the motor 72 is energized for power rotating the spindle 46 and the control member 54. In this respect, the diaphragm 68 serves as a rotary driving member, and the coupling means 56 provides a swivel connection between the spindle and the control member. The approximate swivel point or center of rotation of the coupling means 56 is located slightly above the bearing element 66 closely adjacent the plane of the upper surface of the control member 54. This low swivel point prevents undesirable cocking of the control member 54, and optimum operation of the latter is thereby aiforded. Additionally, the coupling means 56 absorbs end thrust, and accommodates angular misalignment, while assuring axial alignment, between the spindle and the control member. Power rotation of the control member 54 permits required contour corrective action to be effected more rapidly, with a single control member, than has heretofore been possible.

When the corrective treatment has been completed and the contour of the lapping surface of the lapping disc 20 restored to a planar condition, the adjustable sleeve member 44 is threaded upwardly from the position shown in FIG. 3 to the position shown in FIG. 2. As the sleeve member 44 moves axially upwardly, the bearing assembly 52 engages the radial shoulder 48 and raises the spindle 46 whereby to withdraw the contour control member 54 from engagement with the lapping disc 20. The control member 54 is maintained in an elevated position until such time as corrective treatment of the lapping surface is again necessary. During vertical adjustment of the spindle 46, the crown pulley permtis compensating alignment movement of the belt 82, and obviates the need for any spline arrangements.

The apparatus of the present invention is adapted to be used at intervals and for varying periods of time, as may be necessary, to dress the outer annular zone of the lapping surface of the lapping disc 20. Thus, this apparatus, which may be used without interrupting the normal operation of the lapping machine, serves to complement the truing rings in controlling the contour of the lapping surface. Finally, by arranging the contour control member 54 at the rear of the throat of the lapping machine, interference with loading and unloading of the machine is avoided.

Whlie there has been shown and described a preferred embodiment of the present invention, it will be understood by those skilled in the art that various rearrangements and modifications may be made therein without departing from the spirit and scope of the invention.

I claim:

1. In a lapping machine having framework and a lapping disc with an upper horizontal lapping surface rotatably mounted about a vertical axis on the framework, the improvement which comprises a contour control member having a diameter substantially less than the radius of the lapping disc and having a lower horizontal surface engageable exclusively with the outer annular zone of the lapping surface, a vertical floating spindle, means mounting said spindle on the framework above said contour control member, coupling means connecting the lower end of said spindle to said contour control member, and adjustment means at the lower end of said mounting means for selectively engaging and raising said spindle whereby to withdraw said contour control member from engagement with the lapping surface.

2. The improvement of claim 1 wherein the mass of said spindle is such that the free weight thereof bearing on said contour control member serves to provide the desired pressure under which the contour control member is urged into frictional engagement with the lapping disc.

3. The improvement of claim 1 wherein said mounting means is comprised of a vertical tubular casing surrounding a portion of said spindle and secured in said framework, and bearing means between said spindle and said casing; said spindle is provided with a radial shoulder; and said adjustment means is comprised of a sleeve member mounted for axial movement in the lower end of said casing and extend-ing outwardly thereof, and bearing means in said sleeve member and engageable with said spindle shoulder for raising said spindle upon upward axial movement of said sleeve member relative to said'casing.

'4. The improvement of claim 1 including a motor mounted on the framework and having a vertical drive shaft, a crown pulley secured on said driveshaft, and an endless belt extending about said pulley and said spindle for effecting rotation of said spindle and said contour control member.

5. The improvement of claim 1 wherein said contour control member is a circular disc-like member, and said coupling means provides a swivel connection between said spindle and said disc-like member with the swivel point being located closely adjacent the plane of the upper surface of said disc-like member.

6. The improvement of claim 5 wherein said disc-like member is provided with a central conical bearing seat; and said coupling means is comprised of a spherical hearing element engaged in said seat, a flexible diaphragm secured to said disc-like member across the upper surface thereof and engaging said bearing element, and means interconnecting the lower end of said spindle and said diaphragm.

7. The improvement of claim 1 wherein said contour control member includes an annular wear ring engageable with the lapping disc and comprised of a material having a greater abrasion resistance than the material of the lapping disc.

8. In a lapping machine including framework, a lapping disc rotatably mounted about a vertical axis on the framework, a contour control member having a lower horizontal surface engageable with the lapping disc, a vertical spindle mounted on the framework above the contour control member, and coupling means connecting the lower end of the spindle to the contour control member, the improvement which is characterized by said contour control member being a circular disc-like member; and said coupling means comprising a thin flexible diaphragm secured to said disc-like member across the upper surface thereof, and means interconnecting the lower end of said spindle and said diaphragm, whereby a swivel connection is provided between said spindle and said disc-like member.

'9. The improvement of claim 8 wherein said disc-like member is provided with a central conical bearing seat; and said coupling means is comprised of a spherical bearing element engaged in said seat with said flexible diaphragm engaging said bearing element.

10. The improvement of claim 9 wherein said bearing seat is recessed below the plane of the upper surface of said disc-like member, the top surface of said bearing ele ment lies in the plane of the upper surface of said disclike member, and said interconnecting means is comprised of a collar member secured both to the lower end of said spindle and to the central portion of said diaphragm.

References Cited UNITED STATES PATENTS 2,079,076 5/1937 Kranich 51-131 X 2,696,067 12/1954 Leach 51-131 X 3,035,377 5/1962 Bovensiepen 51-109 X 3,290,832 12/1966 Highberg 51-110 X 3,300,907 1/1967 Asaeda -11 X FOREIGN PATENTS 1,054,096 1 0/1953 France.

OTHER REFERENCES German printed application 1,029,699, May 1958.

HAROLD D. WHITEHEAD, Primary Examiner U.S. Cl. X.R. 51-131 

